USC  THIS SITE		The University of South Carolina Department of Electrical Engineering Presents Development of New Materials and Processes for Mechanically-flexible, Microfabricated Neural Interfaces Christian A. Zorman Associate Professor Department of Electrical Engineering and Computer Science Case Western Reserve University Cleveland, Ohio When: 3:30PM on Tuesday, November 27, 2007 Where: 3D05 in Swearingen Center Engineered systems that interface directly with neural tissue offer researchers the opportunity to study, understand and develop interventions for paralysis, Parkinson’s disease, ALS, epilepsy, stroke and many other neurologic impairments. Early approaches utilized "hand-made" electrode structures constructed from silicone, Pt foil, and stainless steel. The next generation designs seek to interface with the nervous system at the neuronal level, thus requiring high density contact arrays. To accomplish this goal, MEMS fabrication technology has recently been utilized to produce Si-based microelectrode arrays. Use of Si as the substrate material enables the integration of the electrode array with CMOS circuitry, providing on-board multiplexing and signal processing capabilities. Despite these advantages, chronic survival of these systems is limited by water and ion absorption. In the peripheral nerves, the rigidity and brittleness of Si restricts the use of these devices due to potential mechanical trauma of neural tissue and damage to the Si devices. For peripheral nerve interfacing, development of mechanically flexible devices made from polyimide and parylene substrates and fabricated using micromachining methods adapted from Si MEMS fabrication technology are being developed. While these polymers exhibit the desired flexibility and biocompatibility, they absorb moisture, making long-term implantation of unprotected structures impractical. Liquid crystal polymer (LCP) and polynorbornene (PNB) are attractive alternatives owing to the fact that their moisture absorption rates are factors of 50 and 28 better that polyimide, respectively. This talk details our effort to advance the use of LCP and PNB as enabling structural materials in implantable microdevices by developing the techniques required to fabricate a micromachined version of a peripheral nerve electrode. The talk will also feature our effort at developing a hermetic sealing technology for these structures using amorphous silicon carbide (a-SiC) thin films. The SiC films are CMOS-compatible, electrically insulating, hydrophobic and are highly resistant to cell and protein attachment, making them an attractive thin film packaging material for smart, wireless, implantable microsystems as well as devices for biofiltration.
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